I am having a very difficult time with these problems. Need help understanding.

PRICE IDollars per large box) 40 36 32 28 24 20 16 12 2 3 4 5 6 7 8 9 10 QUANTITY (Thousands Of large boxes per day) Demand In the following table, fill in the total and marginal revenues that Cardboard Inc. earns for the first three boxes it sells each day. Output Price (Boxes per day) (Dollars per box) Total Revenue (Dollars per day) Marginal Revenue (Dollars per box) 1 2 3 20 20 20 20 The demand curve that Cardboard Inc. faces is identical to which of its other curves? Check all that apply. Its marginal revenue curve Its marginal cost curve Its supply curve Its total revenue curve